1. Field of the Invention
The present invention relates to optical disc drives.
2. Background Art
Capabilities to read and write signals faster with respect to large-capacity optical discs, as represented by Blu-ray (registered trademark) discs, are being demanded of today's optical disc drives. In order to read and write at high speeds, it is preferable that transmission lines be shortened to reduce transmission loss.
On the other hand, flexible lines are used for a large part of read/write signal transmission lines in optical disc drives in order to make the optical pick up movable. Consequently, due to a need to secure a given range of motion, transmission lines physically require a certain length. In addition, flexible lines are used in thin-type optical disc drives used for laptop personal computers and the like in order to enable opening/closing of the disc tray. Such lines also physically require a certain length.
For such reasons, read/write transmission lines of optical disc drives are characterized by the long distance between the signal processing LSI (Large Scale Integration), which processes read/write signals, and the optical pick up. When a read/write transmission line is long, not only does the insertion loss for the transmission line increase, but the effects of reflection at parts with impedance mismatches also bear on lower frequencies. Consequently, waveform degradations are caused in read/write signals, examples of which may include waveform ringing, slower rise/fall times, etc. The effects thereof become more pronounced as the read/write speed is further increased, potentially worsening error rates for reading/writing.
JP Patent Publication (Kokai) No. 2001-84624 A (Patent Document 1), JP Patent Publication (Kokai) No. 2006-24341 A (Patent Document 2), and JP Patent Publication (Kokai) No. 2009-99233 A (Patent Document 3) disclose methods of compensating for such read/write errors.